1. Field of the Invention
This invention relates to the surface modifying agents, surfaces treated with the agents and a method for making surface modifying agents that impart non-wettable, non-stick, friction reducing or other properties to surfaces such as metal, ceramic or other modifiable surfaces.
More particularly, the present invention relates to surface modifying agents, surfaces treated with the agents and a versatile, low cost method for making fluorocarbon-containing surface modifying agents having an .omega.-fluorocarbon-containing tail and an .alpha.-hydroxy, .alpha.-amino, .alpha.-phosphino, .alpha.-thiol or disulfide head formed by coupling an .alpha.-halo-fluorocarbon-containing compounds with an co-alkenyl compound.
2. Description of the Related Art
The synthesis of specifically fluorinated long chain .alpha..omega.-functionalized hydrocarbons remains a challenging enterprise for interfacial scientists. The generation of organized thin films from these molecules offers the opportunity to study and manipulate fundamental properties of fluorinated interfaces, such as wetting, adhesion and tribology. The ability to control the identities of the .alpha..omega.-functionalities using organic synthesis permits atomic-level control over the structure and composition of interfaces formed from these molecules using self-assembly techniques. Organic synthesis thus provides a convenient tool for fine-tuning the interfacial properties.
Several methods have been utilized for the preparation of compounds having perfluorinated terminal segments..sup.1-6 Many approaches have been designed to yield target molecules containing a terminal CF.sub.3 group..sup.7-16 A limited number of methods have, however, provided the opportunity to introduce fluorinated segments of differing lengths.
Brace, for example, investigated the radical addition of several iodoperfluorinates to allylacetate..sup.1,2 This approach was based on initial studies by Park and Lacher.sup.17 and Moore,.sup.18 which utilized ultraviolet light as the radical source. By employing an azo initiator, however, Brace was able to complete the reaction within a few hours compared to five days when using UV light. Brace and previous investigators.sup.19,20 proposed that the reaction proceeded through the formation of a perfluoroalkyl radical that attacked the terminal carbon of the olefinic group. Reduction of the resultant fluorinated iodoacetate with zinc or LiAlH.sub.4 provided a variety of perfluoroalkylated compounds in excellent yields..sup.2
Cloux and Kovats modified the approach developed by Brace to include the addition of 2,2,2-trifluoroethyl iodide to terminal alkenes..sup.21. 2,2,2-Trifluoroethyl iodide is a liquid and made handling the reaction easier than the reaction using gaseous trifluoromethyl iodide. The authors noted that microanalyses failed to give correct and reproducible results.
Several groups have shown that thiol-terminated reagents can be used to change the surface properties of metallic surfaces due to the strong interaction between the thiol moiety and the metal atoms of the surface.
Although radical coupling of .omega.-alkenyl acetates with .alpha.-halo-fluorinated hydrocarbons has been reported and thiol surface modifications have been reported, there is a need in the industry for a cost effective, high yield and versatile method for making fluorinated alkanethiols and/or disulfides and their precursors which can be used to modify surface characteristics, imparting non-wettable, non-stick or low friction surface coatings to the surfaces.